Method and System for Increasing the Thickness of a Carbon Nanotube Sheet Structure

Abstract

A method for increasing the thickness of a sheet of CNTs ( 146, 147, 246, 346 ), comprising: providing a wet sheet of CNTs, wherein the sheet of CNTs is either a continuous sheet of CNTs or a portion of sheet of CNTs, wherein the wet sheet of CNTs is the result of applying a process for manufacturing a sheet of CNTs; separating the wet sheet of CNTs from any filter or support element; drying the wet sheet of CNTs ( 146, 147, 246, 346 ) by applying heat ( 15, 25, 35 ) from a heat source ( 12, 22, 32 ). A method for manufacturing a continuous sheet of CNTs, comprising: in a container ( 41 ) filled with a liquid solution ( 42 ) comprising CNTs at certain concentration, submerging a vacuum tank ( 43 ) having a lower surface forming a grillage; moving an elongated filtering membrane ( 44 ) along the lower surface of the vacuum tank ( 43 ) while vacuum is applied on the elongated filtering membrane ( 44 ) in such a way that in the surface of the filtering membrane ( 44 ) opposed to the surface in contact with the lower surface of the vacuum tank ( 43 ) CNTs are deposited forming a continuous sheet of CNTs ( 45 ) of constant thickness; taking the filtering membrane ( 44 ) together with the continuous sheet of CNTs ( 45 ) out of the container ( 41 ); washing the continuous sheet of CNTs ( 55 ) disposed on the filtering membrane or on a support element ( 54 ) in a second container ( 51 ) filled with cleaning solution ( 52 ); taking the continuous sheet of CNTs ( 55 ) together with the filtering membrane or the support element ( 54 ) out of the second container ( 51 ); separating the continuous sheet of CNTs ( 55 ) from the filtering membrane or the support element ( 54 ); drying the continuous sheet of CNTs ( 55 ) by applying the method for increasing the thickness of a sheet of CNTs.

1 . A method for increasing the thickness of a sheet of carbon nanotubes (CNTs), comprising:
 providing a wet sheet of CNTs, wherein the sheet of CNTs is either a continuous sheet of CNTs or a portion of sheet of CNTs, wherein the wet sheet of CNTs is the result of applying a process for manufacturing a sheet of CNTs,   separating the wet sheet of CNTs from any filter or support element,   drying the wet sheet of CNTs by applying heat from a heat source.   
     
     
         2 . The method of  claim 1 , wherein the wet sheet of CNTs being the result of applying a process for manufacturing a sheet of CNTs, is obtained by soaking in a liquid medium a dry sheet of CNTs already manufactured. 
     
     
         3 . The method of  claim 1 , wherein the sheet of CNTs is continuous or a single portion thereof. 
     
     
         4 . The method of  claim 1 , wherein the drying stage implies a continuous advancing of the sheet of CNTs, or an intermittent advancing thereof, or is static. 
     
     
         5 . The method of  claim 1 , wherein the sheet of CNTs is a continuous sheet of CNTs and the drying of the wet continuous sheet of CNTs is done as follows:
 moving forward the wet continuous sheet of CNTs in a longitudinal direction until a portion thereof is disposed within a drying unit comprising the heat source, the heat source being configured to provide heat to a drying area, the drying unit further comprising screening means for delimiting said drying area, in such a way that the portion of continuous sheet of CNTs is subject to heat only until while it is under the drying area.   
     
     
         6 . The method of  claim 5 , wherein the drying unit further comprises a plurality of rollers configured to rotate freely and to guide the continuous sheet of CNTs along its longitudinal direction, forcing the continuous sheet of CNTs to adopt soft convex and concave curvatures in an alternate way. 
     
     
         7 . The method of  claim 6 , wherein said plurality of rollers comprises a central roller disposed under the drying area and lateral rollers disposed under the screening means. 
     
     
         8 . The method of  claim 5 , wherein the drying unit further comprises two conveyor belts configured to guide the continuous sheet of CNTs in its longitudinal direction, the conveyor belts being longitudinally disposed above and below the continuous sheet of CNTs, respectively. 
     
     
         9 . The method of  claim 8 , wherein at least one conveyor belt is made of a porous material or comprises a grillage, in order to favour the entrance of heat and also to favour liquid evaporation, therefore reducing the drying time. 
     
     
         10 . The method of  claim 1 , wherein the heating source is an infrared irradiation source or a convection source or hot air source, or an ultra-violet (UV) irradiation source or an electrical resistance (ER) radiation source, or a conduction source. 
     
     
         11 . A method for manufacturing a continuous sheet of CNTs, comprising:
 in a container filled with a liquid solution comprising CNTs at certain concentration, submerging a vacuum tank having a lower surface forming a grillage,   moving an elongated filtering membrane along the lower surface of the vacuum tank while vacuum is applied on the elongated filtering membrane in such a way that in the surface of the filtering membrane opposed to the surface in contact with the lower surface of the vacuum tank CNTs are deposited forming a continuous sheet of CNTs of constant thickness,   taking the filtering membrane together with the continuous sheet of CNTs out of the container,   separating the continuous sheet of CNTs from the filtering membrane or the support element, and   drying the continuous sheet of CNTs by applying the method of  claim 1 .   
     
     
         12 . The method of  claim 11 , wherein prior to separating the continuous sheet of CNTs from the filtering membrane or the support element, the method comprises:
 washing the continuous sheet of CNTs disposed on the filtering membrane or on a support element in a second container filled with cleaning solution,   taking the continuous sheet of CNTs together with the filtering membrane or the support element out of the second container.   
     
     
         13 . A system for implementing the method of  claim 1 , the system comprising a drying unit comprising a heat source configured to provide heat to a drying area, the drying area being configured to receive the sheet of CNTs. 
     
     
         14 . The system of  claim 13 , wherein the sheet of CNTs is continuous, the drying area being configured to receive the wet continuous sheet of CNTs as it moves forward in its longitudinal direction, the drying unit further comprising screening means for delimiting said drying area, in such a way that the portion of continuous sheet of CNTs is subject to heat only until while it is under the drying area. 
     
     
         15 . The system of  claim 13 , wherein the drying area further comprises means for preventing deformation of the continuous sheet of CNTs during the drying stage, said means being either a plurality of rollers configured to rotate freely and to guide the continuous sheet of CNTs along its longitudinal direction, forcing the continuous sheet of CNTs to adopt soft convex and concave curvatures in an alternate way, or two conveyor belts configured to guide the continuous sheet of CNTs in its longitudinal direction.